This application relates to an accessory gearbox drive for a gas turbine engine wherein a low spool drives a variable frequency generator along with other components.
Gas turbine engines are known and typically include a pair of spools.
A fan delivers air into a bypass duct as propulsion air and also delivers air into a core engine. Air passing into the core engine reaches a low pressure compressor and then passes to a high pressure compressor. The air compressed by the high pressure compressor is delivered into a combustor where it is mixed with fuel and ignited. Products of this combustion pass downstream over a high pressure turbine rotor.
The high pressure turbine rotor is driven to rotate and rotates the high pressure compressor. A low pressure turbine rotor is downstream of the high pressure turbine and is also driven to rotate. The low pressure turbine rotates with the low pressure compressor as a low speed spool. Further, the low pressure turbine may drive the fan rotor through a gear reduction.
A number of accessories, such as generators, starters, pumps, etc., are powered by accessory gearboxes which are driven to rotate with either the high or low pressure spool. Traditionally, the high pressure spool has driven most of these accessories.
However, this reduces the overall efficiency of the engine. Thus, it has been proposed to drive at least some accessories off the low speed spool.